Conventionally, facilities configured to include a tank for retaining a cold liquefied gas and a plurality of pump barrels for driving out the cold liquefied gas retained in this tank are known. This pump barrel is configured to include a barrel drooped into the tank, a delivery pump provided in an interior of the barrel to suck up the retained liquid, and a pump-discharge pipe for discharging the sucked liquid to outside when driving the delivery pump.
These barrel, delivery pump, and pump-discharge pipe will be deteriorated with age or the like. In this way, the deteriorated components need to be repaired, exchanged for new ones, or altered, namely, renovated.
When renovating the deteriorated components, it is necessary to once fully drive out the cold liquefied gas retained in the tank, renovate the deteriorated components, and then return the cold liquefied gas into the tank. Here, when handling the cold liquefied gas, an equipment management such as temperature control is needed, and many days and costs are required.
An art to solve this problem is disclosed in Patent Literature 1. FIG. 7 is a perspective view showing an example of a conventional purge device for pump barrel 101 disclosed in Patent Literature 1.
As shown in FIG. 7, the conventional purge device for pump barrel 101 is configured to include: a tank 102 in which the cold liquefied gas, namely, liquefied petroleum gas or liquefied natural gas is retained; a tubular barrel 103 drooped in the tank 102; a delivery pump 104 installed in an interior of the barrel 103; a pump-discharge pipe 105 carrying the retained liquid when driving the delivery pump 104; a gas introduction pipe 106 for introducing a gas same as the retained liquid from a vicinity of an upper opening of the barrel 103 into the barrel 103 under pressure; and an inert gas introduction pipe 107 for introducing inert gas from a vicinity of a lower opening of the barrel 103 into the barrel 103 under pressure. The barrel 103 is provided with a foot valve 108 which is released owing to a weight of the delivery pump 104 when the delivery pump 104 is installed.
In such a conventional purge device for pump barrel 101, when pulling out the delivery pump 104 as the deteriorated component, firstly, the delivery pump 104 is slightly moved up to close the foot valve 108. At this time, the retained liquid remains in the barrel 103. Then, the inert gas is introduced into the barrel 103 via the inert gas introduction pipe 107 under pressure. Then, the foot valve 108 is opened, and the retained liquid is pushed back to the tank 102. Next, an active gas is sucked out from the gas introduction pipe 106 to reduce the gas pressure in the barrel 103. After the gas pressure is reduced, the inert gas is introduced into the barrel 103 from the inert gas introduction pipe 107. In this way, after the active gas in the barrel 103 is replaced with the inert gas, the delivery pump 104 is removed. Since the barrel 103 is filled with the inert gas, the delivery pump 104 is removed safely without a risk of ignition by touching oxygen in air or the like.
Thus, with the conventional purge device for pump barrel 101, the delivery pump 104 as the deteriorated component can be replaced, namely, renovated without driving out the liquid retained in the tank 102 while the tank 102 is operated.